18.A.it

　　B.that

　　C.which

　　D.what

　　答案：

　　[解析]which 引导了非限定性定语从句，that 不能引导非限定性定语从句。

　　19.A.reach

　　B.have reached

　　C.be reaching

　　D.be reached

　　答案：B

　　[解析]should have reached 是情态动词的完成形式，从上下文看，有一个非常明显的词By the time ,一般句子中有这个词，那么句子的时态经常用完成时。

　　20.A.destination

　　B.objective

　　C.potential

　　D.conclusion

　　Ⅲ.Reading Comprehension

　　Bill Gates' childhood friends recognized that he was exceptional. Bill especially liked swimming and other sports.One of his summer camp friends recalled, “He was never a nerd or a goof(傻瓜、笨蛋)or the kind of kid you didn’t want your team.We all knew Bill was smarter than us. Even back then, when he was nine or ten years old, he talked like an adult and could express himself in ways that none of us understood.”

　　Bill was also well ahead of his classmates in mathematics and science. He needed to go to a school that challenged(向…挑战)him.Lakeside was Seattle's best school and was noted for its rigorous(严厉的)academic demands, a place where “even the dumb kids were smart.”

　　Lakeside allowed students to pursue their own interests, to whatever extent they wished.The school prided itself on making conditions and facilities available that would enable all its students to reach their full potential. It was the ideal environment for someone like Bill Gates.

　　In 1968, the school made a decision that would change thirteen-year-old Bill Gates’ life and that of many of others, too.

　　At Lakeside the students gained access to a computer-a Program Data processor(PDP)-through a teletype machine. Type in a few instructions on the teletype machine and a few seconds later the PDP would type back its response. Bill Gates was immediately hooked and so was his best friend at the time, Kent Evans, and another student, Paul Allen, who was two years older than Bill.

　　Whenever they had free time, and sometimes when they didn't, they would dash over to the computer room to use the machine.At fourteen, Bill was already writing short programs for the computer to perform. Early games programs such as Tic-Tac-Toe, or Noughts and Crosses, and Lunar Landing were written in what was to become Bill’s second language, BASIC.

　　One of the reasons Bill was so good at programming is because it is mathematical and logical. During his time at Lakeside, Bill scored a perfect eight hundred on a mathematics test.